1. Field of the Invention
The present invention relates to a wing driving apparatus for driving a wing of an airplane.
2. Related Art
There is known a wing driving apparatus for driving the wing in which the wing is driven by all of plural actuators (see JP-A-S64-41498 pp 4 to 7, FIG. 2, for example).
Another wing driving apparatus 900 as shown in FIG. 6 is also known. In the wing driving apparatus, the wing is driven by using some of plural actuators. If any of those actuators malfunctions, the wing is uninterruptedly driven by using an actuator having not been used for driving the wing, instead of the malfunctioning one.
The wing driving apparatus 900 is made up of a steering wing 910, servo actuators 920 and 930 for driving the steering wing 910, a flight controller 950 for generating a drive signal for operating the servo actuators 920 and 930 to drive the steering wing 910, and controller 960 and 970 for receiving a drive signal from the flight controller 950.
The controller 960 operates the servo actuator 920 to drive the steering wing 910 in accordance with the drive signal received. When the controller 960 fails to operate the servo actuator 920 to drive the steering wing 910, it sends a signal through an electric wire 901 to the controller 970.
The controller 970 does not supply current to a solenoid valve 931 of the servo actuator 930 till it receives the signal through the electric wire 901 from the controller 960. And, it operates the servo actuator 930 to follow the steering wing 910. When receiving the signal through the electric wire 901 from the controller 960, the controller 970 supplies current to the solenoid valve 931, and operates the servo actuator 930 to drive the steering wing 910 in accordance with a drive signal received.
Thus, the conventional wing driving apparatus 900 changes over the actuator for driving the steering wing 910 from the servo actuator 920 to the servo actuator 930 under control of both the controllers 960 and 970. Accordingly, when the servo actuator 920 is changed over to the servo actuator 930, the controllers 960 and 970 become asynchronous to each other in their operations, and sometimes control of the flight of the airplane is temporarily lost.
In a specific example, after the servo actuator 920 follows the steering wing 910, the servo actuator 930 does not drive the steering wing 910 immediately. Thus, both the servo actuators 920 and 930 follow the steering wing 910, and the flight of the airplane is temporarily uncontrollable.
In addition, the servo actuator 930 drives the steering wing 910 before the servo actuator 920 follows the steering wing 910, and the servo actuators 920 and 930 are put in a state that those drive the steering wing 910. As a result, the flight of the airplane is temporarily uncontrollable, though infrequently.
Furthermore, the wing driving apparatus 900 does not supply current to the solenoid valve 931 of the servo actuator 930 till the controller 970 receives the signal from the controller 960. Accordingly, it is impossible to sufficiently detect a failure in the construction of the servo actuator 930, such as the solenoid valve 931, till the controller 970 receives the signal from the controller 960.